Thankyou very much audioguru for helping me. I shorted the output , the new and good 2n3055 burned instantly but it was cold! I don't know what to measure so that I could see if the current regulator works. If I will not be able to fix my actually power supply, I think I will build the power supply from bellow. 28 V, 4 A transformer is good? http://www.electronics-lab.com/forum/index.php?topic=7317.1512